I managed to get it installed and working.
These are the steps I took,
1) I upgraded to CX 11.0.2
2) Created a new winxp bottle
3) Installed steam
4) Copied over the dota 2 beta folder from my PC to my bottle
5) Installed dota 2, it recognised that there were existing files already and didn't have to download anything
6) Set launch options -novid and -nod3d9ex
I launched the game and started up a co-op bot game. It loaded up into the game and I could play. There are a few problems atm which I haven't been able to resolve myself.
1) Lucida font for console
2) Graphics anomalies, invokers orbs for instance do not render properly
3) Halfway through my co-op game it crashed, I got an error message saying that dota 2 encountered a problem and needs to close